Re: Why does the addition of one (1) to a positiveInte
Any distinction between types that do not reduce the number of permissible values is close to a placebo ;-) One could argue that (guessing!) that in the case of f:iter(ate) parameters <= 0 could be handled easily by doing nothing. And one might also claim that Googol or Googolplex are not reasonable inpit values; hence explicit range checking might be better than relying on xs:someType,(and result in better error messages, too). YMMV. -W On 29 August 2010 22:46, Michael Kay <mike@xxxxxxxxxxxx> wrote: > >> When I run this I get an error, "The argument to f:iter is xs:positiveInteger, the supplied value is xs:integer" >> >> What is the rationale for this? After all, if I add one (1) to any positiveInteger the result must be a positiveInteger. >> > > There might be logic for saying that the result of xs:positiveInteger + xs:positiveInteger should always be xs:positiveInteger, but a rule that says xs:positiveInteger + xs:integer gives xs:positiveInteger provided that the xs:integer is positive (or provided it is greater than the negation of the first argument?) would be rather arbitrary. > > Generally I would advise against writing a function that expects subtypes of xs:integer as an argument, because you will never be able to supply the argument as a simple literal. These types were designed for validation, not for type-checking programs. That's why, for example, the standard functions insert() and remove() declare the expected type as xs:integer rather than xs:positiveInteger. (It's also why in XSLT 2.0 types such as xs:positiveInteger were excluded from the set of types recognized by a basic XSLT processor). If you want to reject negative integers, do it by conditional code in the body of the function, not by means of the type signature. > > Michael Kay > Saxonica
PURCHASE STYLUS STUDIO ONLINE TODAY!
Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!
Download The World's Best XML IDE!
Accelerate XML development with our award-winning XML IDE - Download a free trial today!
Subscribe in XML format